'Working hard, eh? Watching the Olympics with your laptop on your knee? Taking sneaky naps?" As a novelist and journalist who has worked at home for the past 11 years, to my friends I'm the poster girl for the lifestyle dismissed by Boris Johnson as a "skiver's charter … sitting wondering whether to go down to the fridge to hack off that bit of cheese before checking your emails again."

No commute, no starchy suits, no more missed children's assemblies – the life of a home-worker can indeed seem blissful. Now more of us than ever have the chance to sample the delights of home-working's delights. During the Olympics 1.5 million of the 5 million people who work in London are estimated to be working from home, to ease pressure on public transport. Thousands of civil servants, as well as employees of large companies such as the Royal Bank of Scotland and Sainsbury's, have embraced the chance to send emails in their pyjamas.

Even without the Olympics, we skivers are in the ascendant. Roughly 5.4 million British households now contain one occupant who is working from home, of whom the majority are estimated to be women, often trying to combine earning a living with family commitments. Roughly 50% of these are freelance, the other half employees, but this balance looks set to change as major corporations try to cut costs. Already, British Telecom alone are employing 11,000 home-workers, many of them at senior levels. The move has saved the company £60m.

But at what cost to its employees' mental health? There are certainly pros to home-working. I've conducted phone interviews with film stars while unloading the dishwasher, and attended children's plays while emailing CEOs.

But there's a significant downside – it can rapidly send you slightly bonkers. Increasingly all work is conducted via email rather than phone calls, meaning that during working hours you can literally not hear a human voice for weeks at a time. Before having children, I countered the isolation with a lively evening social life. But once my daughters were born, I was too exhausted to go out at night, and in any case I couldn't afford regular babysitters.

But without either an office in which to chat about last night's telly, or the playgroup network that stay-at-home mothers sensibly cultivate, I felt increasingly alone. I missed irritating colleagues, envied those who could use their commute to decompress. Four years ago things came to a head when I fell ill for weeks with a vicious flu bug.

Researching my latest novel, Ten Minutes to Fall in Love, about a lonely widower finding his feet, I began investigating the health fallout of working alone. I discovered research by Brigham Young University in Utah, which looked at various studies into sociability and showed that lack of human interaction can affect health as badly as smoking 15 cigarettes a day or being an alcoholic. It is as harmful as never exercising and twice as damaging as being obese, says the research.

I took my discoveries as a warning. As soon as I left my bed, I joined a couple of choirs so I was obliged to leave the house twice a week. I forced myself to take regular exercise.

Having previously declined lunch invitations out of guilt that I should be working, I started arranging them. I set a "no pyjamas" rule, although I have never yet emulated Nigella Lawson's home-working dictum of always wearing "morale-boosting" matching bra and pants.

Many home-workers have found salvation in social networking sites such as Twitter and forums such as Mumsnet. I'm guilty of wasting hours on the internet, but to an extrovert like me, online banter is a poor compensation for face-to-face chats. I'm supported by 2009 research by the University of Arizona, which revealed that in less than two decades – in other words, roughly the lifetime of the internet – the number of people saying they have no one with whom to discuss important issues has nearly tripled.

As for Boris's bunking-off prediction – in my experience, the opposite is true. In fact, every home-worker I know is guilty of rarely switching off. It's hard to concentrate on reading a bedtime story to your children when your laptop is just down the hall; I'm writing this article while my husband loafs in front of the evening Olympics next door.

Of course, office workers too are pressured now to respond to texts and emails round the clock, but at least when the day is done they can leave the building – a crucial psychological gear-change. One home-worker I know gets into her car at 6pm and drives round the block to mark the end of her shift. Others rent shared office space, but that's a financial commitment too many for me.

So, Whitehall, enjoy the calm. Your mandarins may return sooner than you think. In the meantime, lonely homeworkers treat yourselves to a chunk of Gorgonzola – and please, enjoy an afternoon nap.

• Ten Minutes To Fall in Love by Julia Llewellyn is published by Michael Joseph.